Process of obtaining ammonia, &amp;c.



PATENTED AUG. 13, 1907.

H. KOPPERS. Pzwoass 0F OBTAINING AMMONIA APPLICATION FILED 0033.14, 1904.

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3 SHEETS-SHEIJT 2 PATENTED AUG, 13, 1 907.

H. KOPPERS. PROCESS OF OBTAINING AMMONIA, &0.

APPLIOATION FILED 001314, 1904.

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PATENTED AUG. 16, '1907.

APPLIGATIOH FILED 001214, 1904.

3SYIBETS-SHEBT3 lawman/.2420 1 M rininnronnorrnns, on EssEN-oN-THE-n nR, GERMANY.

To all whom it may concern:

Be it known that 1, Hammer; Korrnns, a citizen of Germany, residing at Essen-'oii-the Buhr, Germany, have invented an Improved Process of Obtaining Ammonia and Tar, of which the following is a specification.

Hitherto the gases obtained from the dry distillation .or gasification have been treated generally speaking in accordance with two methods for the purpose of separating the by-products, tar-and ammonia. In accordance with the first process the gases were first of all cooled down to atmospheric temperature, thus condensing the tar and gas water, the ammonia remainingin the gas being washed out by means of Water or acid. This treatment yielded a pure tar but it was necessary to convertthe liquid containing the ammonia into a marketable product requiring steam or the reintroduction of heat and so forth. The other method of obtaining the by-products consists in either not cooling the gases at all or only to a very small extent and then treating-them with acid liquors or acids. 7 products, the tar is partially decomposed and the ammonium sulfate is not obtained free from tar. Both processes presentthe important defect that. the two principal constituents, tar and ammonia must undergo common prpcesses gzrhich are only directed to obtaining one of the substances and which have prejudicialteffects as regards the other. '1 f The object of thisinvention is to obtain the b'y-products tar and ammonia in a more simple and economical manner than heretoforepurely and quantitatively, and

the principal feature of the said invention is .thatthe separation of each product takes place at the temperature best adapted therefor, the separation of the tar be- I ing'effected before the ammonia is obtained.

The process is based upon observations 'andexperi- Inents which have been undertaken. As is known, tar

is a mixture of organic bodies of the most various natures, and of sucha compositionthat approximately 5 95 7a to 97% of the constituents boil above 100 Celsius.

New experiments have demonstrated that gases of dry I distillation, such as coke oven and retort gas may be cooled far below? 100 Celsiuswithout water condensing. The dew point for retort gas was 72?;Celsius, that of coke oven gas 85 Celsius (barometer at7GO millimeters). The difference arose-frolnthe higher percentage of water in the coke oven gas, as coking coal in contr'adistinction to gas coal is treated with a certain amount of water (say 14%). Further experiments haveshown that the tarry constituent in the vgasrnay be separated at temperatures of 7 5 to 100 Celsius. .By the treatment of the raw gas attempemtureswhich lie slightly above the dewpoint for separation of water or at that point, i

the tar is separated into one part, about-9a???) of the whole that to say the tar properly so called, which boils above 1L0" Celsius and may consequently he: condensed and separated 'mechgpically pure, and

This process gives impure 3OGESS OF OBTAINING AMMONIA, 850. 0

Patented Aug. 13, 1907;

into a smaller portion (organic bodies, principally heavy benzol and naphthalene) which remains in the gas in the form of vapor. The gas freed from tar which is thus obtained presents a very great similarity to the gases evolved in distilling ammoniacal liquor and may therefore be treated directly for ammonium sulfate in exactly the same way as these latter. 4 t contains organic constituents and gases dissolved, which enter, the acid with the steam.

For the purpose of obtaining the sulfate directly the 1 gas is conducted into sulfuric acid, or into a bath with acid sulfate liquor, which with the object of obviating any condensation from the gas is keptat appropriate temperature the concentration of the bath being about 3033, Bauml The condensation of the water carried in the form of vapor is preventedowing to the fact that the temperature of the gas is maintained above the dewpoint which'has beenpreviously ascertained, or mother words, that thegasis superheated, .so that vaporizationis able to take place even in the acid bath. After the separation of the ammonia the; gases leave the saturation chambers and are cooled .to atmospheric temperature, when the water vapor liq-w comes depositedior thefirst time, thiscondensfy te being a soft pure water which can be made use or. In this process the gases themselves do not suffer. in their composition in any way, so that they maybe treated to form benzol, illuminating gas and srforth, as usuah Now in order that the residuum of organic bodies'i'eferred to aboveand which has. not separated" in the cooling of thesteam-to the dew point and'the treatment for the separation of the tar may notbe' destroyed in the-,sult'uric acid, weak acid liquors'of constant strength as far as phssible are employed 'for saturation, which constancy is insured owing to-the" fact thatacid is supplied continuously as required and the salt separated is likewise withdrawn'contiuuously. If the quantity of acid supplied corresponds exactly to the quantity or acid combinedwith the salt, the desired constancy in the degree of acidity is 7 obtained. This bath which in the manner explained only able to attain. a predetermined degree of corn centration, does not attuckthe tar, especially the" more readily boiling parts; The residuum of organic constituents therefore passes through the process unaltered, is separated with the water and added to the tar which was separated earlier. Any already thickened tar which has entered the saturation bath may beremoved theretrom by means-of anyisuitable me chanical device such as a pump, injector or the like. i

The gas, as it comes from the coke oven, gas retort or regener'ator contains ammonia partially' bound with acids. This part of the ammonia is separatedas a thinf saline solution with the tar and some Water before the 5 passage through the saturation apparatus. It may be: dealt with in numerous ways}; "Thusjior 'i might first of all be treated like gas liquor for obtaining ammonia. Another way is to pump back this saline solution for the time being into the collecting main until it is sufficiently concentrated to flow into the saturation vessels. The-gases'have such a high I temperature in the collecting main on the ovens that the excess heat may advantageously be employed for re-vaporizing the condensed water which is produced on the way to the saturation apparatus.

In many cases, in accordance with the kind and quantity of the condensate, this enriching oi the disrelative increase of steam in the gas is avoided. Fo

If the condensates are very small, care is taken that Y the gases freed from tar are sufiiciently heated and the condensates are allowed-to flow in thin streams into the saturation apparatus where they vaporize. I

As already explained, it is nesessary for the pu pose of efficient tar separation to cool the gas to a temperature at which the saturation with steam is complete (at normal atmospheric pressure this is from.70

to 85 Celsius). Now in order to obviate the great uncertainty which arises in keeping to these temp tures, the procedure may be as follows; Jhe temperature of the raw gas is lowered as much as is necessary for an efficient tar separation, without however departing too much from the dew point for water saturation. After the separation has taken place the temperature of the gas is again raised to such an extent as to permit of ammonium sulfate being directly produced from the saline solution (which invariably contains like quantities of free sulfuric 'acid) with the highest efficiency and excluding as far as possible any condensation during the saturation process. As in this process for separating the tar the gases may be cooled, while obviating the uncertainty already referred to, down to, or even below, the dew point, it is also possible to again raise the temperature for the saturation process to such an extent that not only does condensation not occur, but that even vaporization takes place in other words, tosuperheat the gases. To this end, having regard to the great difference of temperature present, the hot gases coming from the ovens may themselves be used as the source of heat, or heating gas, heat radiating from the walls of the ovens, waste gases or the like may be employed.

The modification described above is especially applicable to the introduction of the process in the case of existing plant, where the gases have hitherto been largely cooled (15 Celsius) and after the separation of the tar submitted -to the usual scrubbing processes.

Omitting this scrubbing the gases, immediately they have been freed from tar, are raised to a temperature of say 85 Celsius by means of the heat of the raw gases, or

to such a' temperature as is besl adaptedfor direct formation of ammonium sulfatoin accordance with the principles of this invention. In a manner exactly analogous to the process described they are then.con-

ducted into the saturation bath and thereupon cooled to atmospheric temperature. The condensate which is formed at the first cooling is preferably converted into ammonia separately.

i The process 'for obtaining the by products withdirect production of sulfate, after separation .of the tar has taken place which forms the basis of this invention, is

characterized broadly by the fact that, the systematic separation of these products is effected at the temperatures most suitable therefor respectively, whereby a temporary transition of temperagire, for the purpose of separating the tar, down to or even below the dew point for the time being for water saturation, may be counterbalanced by a subsequent supply of heat. In doing this an essential feature is the bringing through the process of the residuum of organic bodies which has not been separated, while avoiding decomposition by employment of constant saturation in the acid bath, theregulated supply of fresh acid preventing the attack of organic bodies. Equally important is the subsequent treatment of the saline solution which has been referred to and which takes place by the separation of the ammonia bound with acids, in one or other of the manners explained.

In practice the process described permits of obtaining the by-products almost cost free, as the heat in herent in the gases, which has hitherto been turned to no account, is suflicient for the direct separation of the solid marketable ammonium salt, tar and salt-being obtained pure and quantitatively. What has hitherto been a necessary evil in obtaining ammonia, namely the separate introduction of quantities of fresh water with unnecessary consumption of heat and the formation of a v Figures 1, 3 and 5 are to be regarded as an elevation fol lowing one upon the other, and Figs. 2, 4 and 6 as a similar plan. The raw gases coming 'from the collecting mainfirst of all enter the cooler a, where they are cooled to about the dew point for water saturation. Tliat portion of the tar which condenses at about 100 Celsius then condenses in form of a mist. For separating this condensed tar, which is suspended in the gas analogous to fog floating in the air, the gas containing the floating tar-partidles is first passed through a tar separator and then through filter c. This latter is a vertical cylinder with internal concentric perforated annular jackets (three for example) which serve for the reception of the filtering material. The gas enters the outer annular chamber and filters first through a coarse seams layer of coke and then through a fine layer, the tar separated in the filter and also any water that there may be, flow to the bottom; the contents of the filter the bottom of the vessel where they are bent into semicircular ,parts very finely perforated for the discharge of the gas. An injector e or equivalentdevice raises the salty condensate which has collected at the bottom directly into the centrifugal drier f. The liquor issuing therefrom flows back automatically into the saturation apparatus. The fresh acid is supplied continuously to saturation apparatus d, in regulated quantities, so that the bath does not exceed'a predetermined degree of concentration, so that, as already explained, the residuum of organic bodies still accompanying the gas is not decomposed. An appropriate mechanical device is provided for the removal of any already condensed tar constituents which may have'reached the acid bathl This residuum of organic bodies reaches the coolers g and h with the gas, and here vigorous cooling takes place. The condensate consists of pure water with smallquantities of organic substances whichseparate from the water and which may be conducted to the other products of condensation which were previously separated in a warm state. The water itself is a perfectly soft water, which can be made use of. After tar and ammonia have been obtained in the manner described the gas may be conducted by the exhauste: i into the benzol scrubber k, the further treatment there taking place in the usual manner.

What I claim is:

Process of obtaining ammonia and tar from the gases of the dry distillation or gasiflcation of fuels, consisting constant withdrawal of the deposited salt, conducting the withdrawn salt-to 'a drier, and returning the resulting liquor to the saturation bath, substantially as specified.

HEINRICH KOPPERS.

Witnesses:

\VILLIAM Essnnwnm, Pn'rnn LIE'BEIK. 

